add conjoined_twins model

Author: sebmestrallet

Diff for: CHANGELOG.md

@@ -13,6 +13,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Links to visualize the 3D model with [3dviewer.net](https://3dviewer.net/) ([kovacsv/Online3DViewer](https://github.com/kovacsv/Online3DViewer))
 - `cuboid_tray_with_step` model
 - `encrusted_cube` model
+- `conjoined_twins` model
 
 ### Changed
 

Diff for: README.md

@@ -22,7 +22,8 @@ For STL files I used the default relative deflection of 0.0001.
 
 Name | Thumbnail | Files | Comments
 -----|-----------|-------|---------
-`encrusted_cube` | <div align="center"><img src="encrusted_cube/thumbnail.png" width="300"/><br/><a href="https://3dviewer.net/#model=https://github.com/LIHPC-Computational-Geometry/nightmare_of_polycubes/blob/main/encrusted_cube/labeled_mesh.glb" target="_blank" rel="noopener noreferrer">3D viewer ↗</a></div> | [.hdf](encrusted_cube/SALOME_Study.hdf) <br/> [.py](encrusted_cube/SALOME_Shaper.py) <br/> [.step](encrusted_cube/CAD.step) <br/> [.brep](encrusted_cube/CAD.brep) <br/> [.stl](encrusted_cube/CAD.stl) <br/> [.obj](encrusted_cube/triangle_mesh.obj) | The labeling is justly classified as invalid (there are 4-connected corners with incident boundaries of the same axis) according to the "simple orthogonal polyhedra" criteria [^5][^1]. But the issue is that the common processing for invalid corners (local relabeling) will result in a high distorsion, whereas a global operator (retracing of incident boundaries) would be better. Model inspired by ABC n°00001525 [^6].
+`encrusted_cube` | <div align="center"><img src="encrusted_cube/thumbnail.png" width="300"/><br/><a href="https://3dviewer.net/#model=https://github.com/LIHPC-Computational-Geometry/nightmare_of_polycubes/blob/main/encrusted_cube/labeled_mesh.glb" target="_blank" rel="noopener noreferrer">3D viewer ↗</a></div> | [.hdf](encrusted_cube/SALOME_Study.hdf) <br/> [.py](encrusted_cube/SALOME_Shaper.py) <br/> [.step](encrusted_cube/CAD.step) <br/> [.brep](encrusted_cube/CAD.brep) <br/> [.stl](encrusted_cube/CAD.stl) <br/> [.obj](encrusted_cube/triangle_mesh.obj) | The labeling is justly classified as invalid (there are 4-connected corners with incident boundaries of the same axis) according to the "simple orthogonal polyhedra" criteria [^5][^1]. But the issue is that the common processing for invalid corners (local relabeling [^3]) will result in a high distorsion, whereas a global operator (retracing of incident boundaries) would be better. Model inspired by ABC n°00001525 [^6].
+`conjoined_twins` | <div align="center"><img src="conjoined_twins/thumbnail.png" width="300"/><br/><a href="https://3dviewer.net/#model=https://github.com/LIHPC-Computational-Geometry/nightmare_of_polycubes/blob/main/conjoined_twins/labeled_mesh.glb" target="_blank" rel="noopener noreferrer">3D viewer ↗</a></div> | [.hdf](conjoined_twins/SALOME_Study.hdf) <br/> [.py](conjoined_twins/SALOME_Shaper.py) <br/> [.step](conjoined_twins/CAD.step) <br/> [.brep](conjoined_twins/CAD.brep) <br/> [.stl](conjoined_twins/CAD.stl) <br/> [.obj](conjoined_twins/triangle_mesh.obj) | Simplified configuration of the previous model.
 `cuboid_screw_thread` | <div align="center"><img src="cuboid_screw_thread/thumbnail.png" width="300"/><br/><a href="https://3dviewer.net/#model=https://github.com/LIHPC-Computational-Geometry/nightmare_of_polycubes/blob/main/cuboid_screw_thread/labeled_mesh.glb" target="_blank" rel="noopener noreferrer">3D viewer ↗</a></div> | [.hdf](cuboid_screw_thread/SALOME_Study.hdf) <br/> [.py](cuboid_screw_thread/SALOME_Shaper.py) <br/> [.step](cuboid_screw_thread/CAD.step) <br/> [.brep](cuboid_screw_thread/CAD.brep) <br/> [.stl](cuboid_screw_thread/CAD.stl) <br/> [.obj](cuboid_screw_thread/triangle_mesh.obj) | Introduced in [^2] and mentioned in appendices of [^3]. <br/> Labeling-based approaches [^1][^3] will collapse the two parts of the slope, constrained to the same top and bottom planes.
 `cuboid_torus_with_step` | <div align="center"><img src="cuboid_torus_with_step/thumbnail.png" width="300"/><br/><a href="https://3dviewer.net/#model=https://github.com/LIHPC-Computational-Geometry/nightmare_of_polycubes/blob/main/cuboid_torus_with_step/labeled_mesh.glb" target="_blank" rel="noopener noreferrer">3D viewer ↗</a></div> | [.hdf](cuboid_torus_with_step/SALOME_Study.hdf) <br/> [.py](cuboid_torus_with_step/SALOME_Shaper.py) <br/> [.step](cuboid_torus_with_step/CAD.step) <br/> [.brep](cuboid_torus_with_step/CAD.brep) <br/> [.stl](cuboid_torus_with_step/CAD.stl) <br/> [.obj](cuboid_torus_with_step/triangle_mesh.obj) | Introduced in [^2] I believe. <br/> Here too labeling-based approaches [^1][^3] will not detect any invalidity and crush the step into the z-axis plane.
 `cuboid_tray_with_step` | <div align="center"><img src="cuboid_tray_with_step/thumbnail.png" width="300"/><br/><a href="https://3dviewer.net/#model=https://github.com/LIHPC-Computational-Geometry/nightmare_of_polycubes/blob/main/cuboid_tray_with_step/labeled_mesh.glb" target="_blank" rel="noopener noreferrer">3D viewer ↗</a></div> | [.hdf](cuboid_tray_with_step/SALOME_Study.hdf) <br/> [.py](cuboid_tray_with_step/SALOME_Shaper.py) <br/> [.step](cuboid_tray_with_step/CAD.step) <br/> [.brep](cuboid_tray_with_step/CAD.brep) <br/> [.stl](cuboid_tray_with_step/CAD.stl) <br/> [.obj](cuboid_tray_with_step/triangle_mesh.obj) | Similar to the previous model (the step will still be crushed), but of genus 0.